The present invention relates to a biodegradable extracting container. More particularly, the present invention relates to a biodegradable extracting container for extracting a drink material, for example, coffee, black tea, green tea, or oolong tea, with hot water or cold water.
In conventional extracting bags for extracting a drink material, for example, coffee, black tea, green tea or oolong tea with hot water or cold water, the bags are usually formed from woven fabrics, nonwoven fabrics comprising synthetic fibers selected from, for example, nylon filaments and polyester filaments, or paper sheets.
After the synthetic fiber bags are used to extract the drink material such as tea, the used bags are discharged as home waste. In this case, as the synthetic fibers from which the bags are formed, per se have no biodegrability, the used bags are necessarily sent to a reclaiming treatment or to a burning and then reclaiming treatment, and this necessity causes an increase in the amount of wastes which is currently a social problem.
Compared with the synthetic fiber bags, the paper bags exhibits a biodegradability and thus the discharge of the used paper bags does not cause the above-mentioned problems.
When the drink material is contained in a bag formed from conventional synthetic fibers or paper sheets, and stored in storing surroundings having a high humidity and a high temperature, the problem such that in the contained material in the bag, various molds and bacteria grow thereon due to non-antibacterial property of the bag itself. In the prior art, to solve the above-mentioned problem, the bag is covered with a non-gas-permeable sheet by which the bag is protected from moisture.
For this covering, complicated and costly procedures are needed.
It is known that the anti-bacterial property can be imparted to the synthetic fibers by knead-mixing an antibacterial agent into a fiber-forming material during filament-forming procedures, or fixing the antibacterial agent on the surfaces of the filaments made by the filament-forming procedures with a resinous binder. The above-mentioned application of the anti-bacterial agent to the synthetic fibers are not appropriately in view of the possibility of such an occurrence that the antibacterial agent is extracted into hot water or cold water during an extracting procedure, and the fragrance and safety of the extracted drink are degraded.
Also, before the used extracting bag is discarded as a waste, the extraction residue in the bag is retained in a water-holding condition. During this stage, as the conventional fiber bag has no antibacterial property, various bacteria and molds are grown on portions of the residual material contacting with water, and a slimy substance and an offensive odor are generated. Therefor, when the used bag is discharged as waste, a strong offensive odor is felt and a discharging operation becomes difficult. Particularly, in the summer season, the bacteria vigorously propagate and, thus, there is a possibility of occurrence of poisoning through hands brought into contact with the waste.
As stated above, the extracting bag formed from the conventional synthetic fibers does not exhibit a biodegrading property and, therefore, when tea leaves contained and sealed in an extracting bag are stored, for the purpose of inhibiting the propagation of the various mold and bacteria, the extracting bag is packaged with a water-proof sheet. However, the above-mentioned packaging is disadvantageous in that complicated and costly procedures are needed. Also, in this case, before the extracting bag is used, a procedure of removing the packaging sheet from the bag is needed, and the removed packaging sheet which is completely unnecessary for the extraction using the extracting bag must be discharging. Namely, the use of the packaging sheet is disadvantageous in that a discharging procedure is needed and a waste is generated.
Also, with respect to the treatment of the used drink-extracting bags, it should be noted that, as the conventional synthetic fiber bags do not have biodegradability, the used bag waste must be sent to a reclaiming treatment or a burning and then reclaiming treatment. This necessity causes an increase in the amount of waste.
Also, the conventional extracting bags formed from the synthetic fibers are disadvantageous in that various bacteria and molds propagate on the extraction residue in the used bags so as to cause slimy substances and offensive odor are generated, and there is a possibility of occurrence of poisoning through the hands contacting the used bags.
An object of the present invention is to provide an antibacterial, biodegradable extracting container formed from an extract-filtering material which can prevent propagation of bacteria and mold on the material contained in the container and to be subjected to extraction, and which, per se, is bio-degradable.
The antibacterial, bio-degradable extracting container of the present invention has a filtering surface formed from a water-permeable sheet selected from woven and knitted fabrics, and is characterized in that fibers from which the water-permeable sheet is formed comprises, as a principal component, an antibacterial, biodegradable polylactate polymer, and have a thickness of 1 to 100 dtex.
In the antibacterial, biodegradable extracting container of the present invention, the filtering surface may form at least a portion of surfaces of a bag-formed container.
In the antibacterial, biodegradable extracting container of the present invention, the water-permeable fabric sheet from which the filtering surface is formed preferably has a cover factor K of 1600 to 6400, determined in accordance with the following equation:
K=(Nxc3x97(A)1/2/T)+(Mxc3x97(B)1/2/S)
wherein, N represents a warp density (yarns/10 cm), M represents a weft density (yarns/10 cm), A represents a thickness (dtex) of the warp yarns, B represents a thickness (dtex) of the waft yarns, T represents a specific gravity of the warp yarns and S represents a specific gravity of the weft yarns.
The filtering surface of the antibacterial, biodegradable extracting container of the present invention is formed from a water-permeable sheet selected from water-permeable woven and knitted fabrics formed from fibers comprising an antibacterial, biodegradable polylactate polymer and having a thickness of 1 to 100 dtex.
In the present invention, the term xe2x80x9cantibacterial propertyxe2x80x9d refers to a characteristic of preventing propagation of bacteria and molds on a material contained in the extracting container of the present invention and to be subjected to extraction, namely, coffee particles or various types of tea leaves.
Namely, the extracting container of the present invention has a characteristic of controlling the propagation of bacteria and molds and exhibits a bactericidal activity value of O or more. The bactericidal activity value is a parameter representing an antibacterial property, determined in JIS L 1902. When the bactericidal activity value is less than 0, the bacteria can propagate and thus the object of the present invention cannot be attained.
The antibacterial, biodegradable extracting container of the present invention has a filtering surface through which an extract solution obtained by extracting the material contained in the container and to be extracted with cold water or hot water, is filtered. The filtering surface is formed from a water-permeable sheet selected from woven and knitted fabrics. The fibers from which the woven and knitted fabrics are formed comprises, as a principal component, an antibacterial, biodegradable polylactate polymer, and has a thickness of 1 to 100 dtex. Preferably, 50% by weight or more of the fibers from which the filtering surface of the water-permeable sheet are formed from the antibacterial, biodegradable polylactate polymer. More preferably, 100% by weight of the filtering surface-forming fibers are formed from the polylactate polymer.
The polylactate polymer usable for the present invention is one prepared by polymerizing lactic acid or dimer lactide of lactic acid which is used as a monomer. The polymer may be selected from homopolymers of optical isomers D and L, copolymers of the optical isomers D and L with each other or a mixture of the homopolymers and the copolymers.
For the purpose of imparting an antibacterial property to the extracting container, the inventors of the present invention carried out an extensive study on various polymers, and, as a result, found that the above-mentioned polylactate polymer exhibits an excellent antibacterial property and is optimum as a material for forming the extracting container.
The fibers comprising, as a principle component, preferably in a content of 50% by weight or more, the polylactate polymer may be in the form of multifilaments, monofilaments or staple fibers. The staple fibers may be employed in the form of spun yarns, or in the form of composite yarns comprising the staple fibers and the filaments. There is no limitation to the cross-sectional profile of the fibers and filaments. Usually, a circular cross-sectional profile is preferred. In consideration of the meaning and knitting property of the fibers, the flexibility and extracting property of the container (bag), extracting property of the container and degree of filter leakage of the extract in the container, the thickness of the polylactate polymer fibers must be in the range of from 1 to 100 dtex, preferably 5 to 50 dtex.
If the thickness is less than one dtex, while the resultant water-permeable sheet exhibit a satisfactory flexibility, in the water-permeable sheet selected from the woven and knitted fabrics, slippage of the yarns easily occurs, and when the woven or knitted fabric is constituted in an increased yarn density, the weaving and knitting efficiency is decreased, and the resultant fabric is disadvantageous in that in the extracting procedure, clogging of the filtering surface occurs and the filtering efficiency becomes unsatisfactory. Also, if the thickness is more than 100 dtex, the resultant water-permeable woven or knitted fabric exhibit an increased stiffness and an insufficient flexibility, and when the weaving or knitting density is decreased for the purpose of increasing the flexibility of the fabric, the resultant fabric has large gaps between the yarns, and allows the solid fraction in the container to leak through the filtering fabric surface during the extracting procedure, namely, a disadvantageous filter leaking phenomenon occurs.
In the case where, in the extracting container of the present invention, the water-permeable sheet produced from the polylactate polymer fibers is a woven fabric, the cover factor K is preferably 1600 to 6400, more preferably 3200 to 4000. The cover factor K is determined in accordance with the following equation.
K=(Nxc3x97(A)1/2/T)+(Mxc3x97(B)1/2/S)
wherein, K represents a cover factor of the woven fabric, N represents a warp density (yarns/10 cm), M represents a weft density (yarns/10 cm), A represents a thickness (dtex) of the warp yarns, B represents a thickness (dtex) of the weft yarns, T represents a specific gravity of the warp yarns and S represents a specific gravity of the weft yarns, of the woven fabric. If the cover factor K of the woven fabric for the water-permeable sheet is less than 1600, the filter leak in the extraction may be too much, and if the cover factor K is more than 6400, the clogging of the filtering surface may occur during the extraction.
In the extracting container of the present invention, there is no limitation to the form and dimensions thereof, as long as the container is provided with at least one filtering surface formed from the water-permeable sheet as specified above. The container may be a bag-formed container (bag) formed from the specific water-permeable sheet. The bag-formed container may be a extracting bag having only front and back filtering surfaces, or another extracting bag having front and back filtering surfaces, right and left side gore filtering surfaces and a bottom gore filtering surface. Further the extracting container may be in the form of a polyhedron, for example, a tetrahedron or hexahedron (box-form), or a cylinder. In this case, the polyhydronal or cylindrical container must be provided with at least one extracting surface formed from the water-permeable sheet specified in the present invention. Alternatively, the extracting container of the present invention may be provided with, in addition to the bag-formed container formed from the specific water-permeable sheet, a supporting member of the bag-formed container.
Where the extracting container of the present invention is an extracting bag, the bag is produced by cutting the specific water permeable sheet into a desired size, the cut sheet is folded double and two side edges are bound by a heat melt-welding method or high frequency welding method or ultrasonic welding method to form a bag, while a top edge is maintained open, to provide an inlet for feeding a material to be extracted into the resultant bag. The material to be extracted is placed into the bag, and the open top edge of the bag is sealed by the above-mentioned welding method. The extracting container in another form can be produced by using the specific water-permeable sheet as defined in the present invention by a conventional container-producing method.
A hanging member attached to the extracting bag comprises a hanging thread comprising, for example, twisted multifilament or monofilament yarn or a spun yarn of staple fibers and a tag made from a sheet material, for example, a paper sheet, and connected to a top end of the hanging thread. Preferably, the hanging thread and the tag are produced from a biodegradable material, for example, polylactate polymer or cellulose, to enable the hanging member attached to the extracting bag to be completely biodegraded.
The water-permeable sheet from which the filtering surface of the extracting container of the present invention is produced from synthetic fibers comprising, as a principal component, a polylactate polymer. When the material to be extracted, for example, coffee particles or tea leaves, is wetted with water, or after the extraction is completed, the polylactate polymer fibers in the filtering surface exhibit a performance of preventing the propagation of the bacteria and molds adhered to the wetted extracted material, and after the used extracting container is discarded, the polylactate polymer fibers are biodegraded. Also, as the polylactate polymer has a melt-bonding property, the polylactate polymer fiber sheet can be melt-bonded by the conventional heat welding method, high frequency welding method, and ultrasonic welding method. Accordingly, the extracting container of the present invention enables the material to be extracted, contained in the container, to be maintained fresh during storage thereof without packaging the material with a non-gas-permeable material, and after using, the propagation of saprogens, for example, staphylococcus aureus and pseudomonas aeruginosa, and molds and the generation of putrid odor and slimy substance. Also, when the extracting container is discarded after use, the container is biodegraded by degradation bacteria in the earth and disappears. Namely, the polylactate polymer is hydrolysed to split the molecular chains thereof in the initial stage of the biodegradation. The hydrolysis is carried out at an accelated rate under high temperature and high humidity conditions, and at a low rate at room temperature. After the splitting of the polymeric molecular chains has progressed to a certain extent, the hydrolysis product is further decomposed by the action of the natural degradation bacteria, for example, heat-resisting spore bacteria and/or anaerophytes. It is noted that almost of all of the degradation bacteria exist in the earth and few degradation bacteria exist in the air. Thus, the bacteria existing in the air substantially do not degrade the polylactate polymer.
The extracting container of the present invention can be rapidly biodegraded, after use, by using a conventional compost treatment apparatus available on trade. In this case, the compost treatment is usually carried out at a temperature of 45 to 100xc2x0 C., preferably 50 to 80xc2x0 C. If the treatment temperature is less than 45xc2x0 C., not only the degradation rate may be too low, but also propagation of various bacteria other than the degradation bacteria effective on the biodegradation may be promoted and thus the treatment surroundings may become insanitary and the degradation bacteria may be affected by the non-degradation bacteria. If the treatment temperature is more than 100xc2x0 C., the handling and surroundings may be dangerous in view of prevention of disasters, and/or the degradation bacteria may die out. To adjust the treatment temperature as mentioned above, a heater may be used or for certain types of bacteria, or metabolic heat generated by the degradation bacteria may be utilized.
The degradation bacteria usable for the compost treatment at a relatively high temperature as mentioned above are preferably selected from thermophilic bacteria, for example, bacillus brevis.